Protecting intellectual property.  The internet 
is not a lawless no-space.  When you wurf the 
internet you are subject to the same laws as to 
anything else in your daily life.  International 
Copyright Law protects scans you make of your 
cels, and hence having someone steal them *is* a 
crime.

ISPs *do* care.  Believe me, you ask them to take 
a site down for stolen images and they will.